Characteristics of Coalbed Methane Produced Water in Alabama

1. Characteristics of Coalbed
Methane Produced Water in
Alabama
Nick Tew
Alabama State Geologist/Oil and Gas Board Supervisor
Geological Survey of Alabama
State Oil and Gas Board of Alabama
Atlantic Council
Fossil Fuel Produced Water Workshop
Washington, DC
June 24-25, 2013

2. Alabama’s Fossil Fuel Energy Endowment
 Coal
 Black Warrior Basin Coal Measures
 Coastal Plain Lignite (low-rank coal)
 Oil
 Conventional
 SW Alabama Oil and Condensate
 Black Warrior Basin Oil
 Unconventional
 Oil Sands of North Alabama
 Oil Shale of North Alabama
 Natural Gas
 Conventional
 SW Alabama
 Black Warrior Basin
 Unconventional
 Coalbed Methane of Black Warrior Basin
 Paleozoic Gas Shales of North Alabama
Geology of
Alabama

3. Significant Activity Areas

4. Coalbed Methane in Alabama
• Degasification experiments for mine safety began in the
mid-1970s.
• Commercial production began in 1980.
• Currently close to 5,000 active wells in 20 fields.
• Annual gas production between 105 and 121 Bcf for the last
20 years.
• More than 2.1 Tcf cumulative gas production.
• More than 1.7 billion barrels of water produced.

5. Alabama CBM Fields

6. Cumulative Gas Production
from 1980-2009
Cumulative Water Production from
1980-2009
Cumulative Gas and Water
Production

7. Development and Production
• Drilling and hydraulic fracturing currently uses “city” water
• Usually trucked to location
• Additional water during production is not needed

8. Co-Produced Water
• CBM production is pressure driven and usually requires
dewatering of coals to lower hydrostatic pressure for gas
production.
• Water production is generally high early in a well’s life and
decreases rapidly.
• Gas production generally peaks in the first few years, after
peak water, then decreases.
• High water production can limit how often and how much a
well can be pumped, limiting gas production.

9. Peak Gas and Water
Production

10. 0
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waterProduction(bbl)
Gasproduction(Mcf)
Reese-Taurus-91-21-08-07-04 #1684
(OGB PN 10009)
Monthly Production
Gas
Water

11. 0
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WaterProduction(bbl)
GasProduction(mcf)
USX 34-16-48
(OGB PN 10892-C)
Monthly Production
Gas
Water

12. Co-Produced Water
• As new areas of production come on line, water production
is relatively high.
• As an area reaches maturity, the water production will slow
and level off.
• Some areas, with high recharge rates, will continue to
produce significant water volumes over the life of the well.
• In and around mining, where water levels have been drawn
down prior to drilling, wells produce little to no water.

13. Water production
through time

14. Water production
through time

15. Water Treatment and Disposal
• In-stream disposal is the dominant practice in the Black
Warrior Basin.
• Prior to disposal, water is treated to remove
silt, clay, iron, and manganese compounds.
• Underground injection can augment in-stream disposal in
areas of highly saline water; however, currently all produced
water is disposed of in-stream.
• Potential beneficial uses exist for produced water with less
than 3,000 mg/L TDS.
• In the southwestern CBM fields, water is more saline and
limits the ability to pump wells.

16. Produced Water
Discharge Points

17. Water Chemistry
 Major constituents:
 Mostly sodium-chloride, some areas are dominated by sodium bicarbonate
waters.
 Generally low in sulfate, magnesium, and calcium.
 Almost all wells exceed secondary drinking water standards for TDS (500
mg/L), but the average well is in a USDW (<10,000 mg/L).
 Average levels of barium, cadmium, fluoride, lead, and thallium
exceeds the drinking water MCL; average levels of zinc and
manganese exceed the secondary drinking water regulations.

19. CBM Produced Water in Alabama
 Potential Beneficial Uses:
 Aquaculture and irrigation water, in particular shrimp farming
 Water for drilling and hydraulic fracturing
 Municipal supply
 Alternative water treatment:
 Reverse osmosis systems
 Artificial wetlands (Clemson-Chevron research)
 Alternative to in-stream disposal:
 SWD wells, however, no consistent high capacity zones
identified

20. Acknowledgments
 GSA CBM Produced Water Project funded by the U.S.
Dept. of Energy, Office of Fossil Energy, NETL, DOE
Award Number DE-FE0000888.
 GSA Research Team: Marcella McIntyre-
Redden, Steve Mann, Jack Pashin (now at OK
State), David Kopaska-Merkel, Ashley Williams, and
Mac McKinney.